Lights out at Eiheiji
As suggested by the saying “Awake half a mat, asleep a whole mat,” each person’s tatami represents the personal space alloted to him in the Monk’s Hall. For a trainee monk his mat is indeed the universe.
… At Eiheiji, the word for lights-out – kaichin – means literally “opening the pillow”. It goes back to the old days in Zen monasteries when monks used to sleep on folding wooden pillows. Today the practice of unfolding the pillow for sleep survives only in this word.
… No mattresses are used at Eiheiji, either. Instead each person has two quilts, which must take up no more than the allotted space. Before lying down you align them so that they overlap slightly, then roll them into a tube, which you must tie snugly at the bottom and loosely at the top before wriggling inside. Finally, you ties the covers once more around your chest, lie on your right side, and go to sleep. This position is chosen because it is the same position in which Buddha entered nirvana. Lying faceup is called “corpse sleep” and lying facedown “debauched sleep”. They are frowned on equally.